This invention relates to dedicated devices having a processor that executes a set of instructions, and more particularly to the loading of the instructions for the processor.
Many devices employ a processor executing instructions contained in embedded code. A small sampling of such devices include printers, copying machines, video cassette recorders (xe2x80x9cVCRxe2x80x9d), thermostats, and a variety of systems in automobiles such as the ignition system. Traditionally, these dedicated devices store their instruction sets in a fixed form in a non-volatile memory, such as read-only memory (xe2x80x9cROMxe2x80x9d). More recently, these dedicated devices have taken advantage of reprogrammable non-volatile memories, such as erasable programmable memory (xe2x80x9cEPROMxe2x80x9d), electronically erasable PROM (xe2x80x9cEEPROMxe2x80x9d), and flash RAM to store the instruction sets. Programmable memories allow the dedicated device to be reprogrammed without the expense and inconvenience of replacing a ROM or motherboard.
Dedicated devices typically have the complete instruction set for running the device stored in the non-volatile memory. Such an approach has a number of distinct drawbacks. For instance, storing the executable code for anything but the most simple device requires a significant amount of non-volatile memory. The dedicated device may not be upgradable or may be difficult to upgrade, requiring the entire instruction set to be reprogrammed. Such an upgrade may take a considerable period of time and may lead to corrupted executable code rendering the device permanently inoperative. This is particularly a problem when the size of the program is considerable. Additionally, the user of a dedicated device my not be aware of a significant upgrade and may be running old, incompatible or corrupted programs.
Under one aspect of the invention, a dedicated device such as a printer may have a small amount of non-volatile memory to store a communications kernel. Upon startup, a microprocessor in the dedicated device executes the communication kernel to prompt a host, such as a server, to download a setup kernel to a memory in the dedicated device. The microprocessor may determine a checksum value for return to the host to verify that the setup kernel was correctly received. Upon verification of the setup kernel, the microprocessor may execute the instructions of the setup kernel to determine a set of operational characteristics of the dedicated device. For example, the microprocessor may interrogate the hardware elements of the dedicated device to determine a set of hardware characteristics. The microprocessor may also interrogate the dedicated device to determine the value of a set of user selectable setup options. The microprocessor may further interrogate the dedicated device or a nonresident register for ownership attributes to, for example, determine ownership and access rights to selected modules and software.
Upon determining the operational characteristics, the microprocessor may select a number of library modules based on the operational characteristics and link the library modules to create an operational program for the device. The microprocessor may download some, none, or all of the library modules and may link both resident and nonresident library modules.
The resulting device is specifically configured to take advantage of all of the hardware components contained in the device and to run the most recent versions of software. The device is further configured to operate in accordance with all user selected options and to allow access to any functionality that the user has a right to access.
For example, in the case of a printer, appropriate library modules may be linked to match the hardware characteristics of the printer, such as the printhead and the transport mechanism. The linked libraries may also match user selectable setup options, such as page size, duplex or nonduplex printing, and darkness or contrast. Further, in the case of a printer, selected modules may be linked to provide access to certain fonts or print drivers that the user has purchased or licensed.
In a further aspect of the invention, the library modules are dynamically linkable to reconfigure the software as the operational characteristics change. For example, the user of the dedicated device may vary the user selectable setup options or may pay a fee to access a particular piece of code such as a particular font.
Thus, the device employs a dual kernel system, employing a minimal communications kernel stored in non-volatile memory to download a setup kernel that determines the operating characteristics and selectives or links library modules based on the determined characteristics. Each dedicated device can be customized to provide the precise functionality that the user requires. The resulting dedicated device is easily upgradable and permits easy and efficient testing and debugging. Such testing and debugging may take place over a network, such as the Internet.